Preparation of chemiluminescent composition of matter



Patented Nov. 9, 1948 Y UNITED STATES PATENT OFFICE PREPARATION OF CHEM ILIMINESCENT COMPOSITION OF MATTER Harold T; Lacey,-Plainficld, and Robert E. Brouillard, Somerville, N. 1., assignors to American: 'Cyanamid Company, New York, N. Y., acorpora-tionof Maine N Drawing. Application February 19, 1944, SerialNo.523,157 1 This invention relates to :an improved process of preparing chemiluminescent materials. More particularly, the invention refers to a process of Preparing nitro-1,4-dioxo-tetrahydrophthalazines such as the and G-nitro derivatives and the corresponding 5- and S-amino-1,4-dioXo-tetrahyd-rophthalazines and to a product so produced.

"Various chemiluminescent compositions have been prepared, making use of materials which give off light when oxidized in aqueous solution.

One of the best materials for this purpose has been found to be 5-amino-1,4-dioxo-tetrahydrophthalazine which may be represented by the formula:

amino-1,4 dioxotetrahydrophthalazine is from phthalic anhydride. 1 The latter is first nitrated with mixedacid to produce a mixture of 3- and 4- nitrophthalic anhydrides andthe 4-isomer is then extracted irom the mixture with water, in which it, is considerably more soluble than theB-derivative. The remaining 3-nitrophthalic acid is then condensed in aqueous medium with hydrazine sulfate, usually in the presence of a. suitable acid binder such as sodium acetate or the like. The condensation results in the formation of 3-nitro- N-amino phthalimide which may .be' represented by the formula:

2 Claims. (on. 260450) Bytmolecular rearrangement, this product is oonverted to the isomeric 5-nitro-l, i-dioxo-tetrahydrophthalazine oftheformula: it

IITOz O Subsequently, the nitro derivative is reduced to the corresponding 5-amino derivative by any suitable procedure. H I

Condensation of 3 nitrophthalic acid with bydrazine sulfate and the subsequent rearrange-f ment of the resulting 3-nitro-N-amino phthalimide are difiicult operations to carryout from a technical .point of. view. Both the nitrophthali-c acid and the hydrazinensulfate are but sparingly soluble in water and the product, 3-nitro-N-amino phthalimide, is similarly difiicultly. soluble in water. Furthermore, the product is obtained in an aqueous slurrywhich must be evaporated to dryness and heated to C. in carrying out the subsequent rearrangement. Not only is consider} able time required: but the yields are not as high as desired. While these operations may be quite. readily carried out in thelaboratory, theybffer obviously difiicult problems ifthey are to be done i on a commercial scale.

Because of these technical ditficulties, the production of suitable 5-amino-1,4-dioxo-tetrahydro hthalazine for practical use has been both troublesome and unsatisfactory. It. is, therefore, the principal objection of the present invention to provide a suitable process for carrying out this production in a simpler and faster manner and one which will enable the production of greater amounts of useiulmaterial.

These desiredobjects are achieved by taking advantage of several rather surprising discoveries. The first is that the condensation of either theB or thee-nitrophthalic acid can be carried out at moderate temperatures in concentrated sulfuric acid. Further, it has also been found that the subsequent rearrangement may be accom plishedin the same medium. Both reactions proceed smoothly and without difiiculty, thus eliminating the troublesome steps of the prior art.

which were set forth above.

A still further practical advantage is obtained through the discovery that in spite of the prior .art'teaching'that .the S-aminoderivative does not luminesce with the brilliance of the 5-amino com-l pound, a mixture of the two is substantially equal to be in brilliance to the isolated B-amino compound. Thus it is perfectly feasible to treat the mixture of 3- and l-nitrophthalic anhydrides obtained from the phthalie anhydride-mixed acid reaction. By taking advantage of these findings it is readily possible not only to eliminate the separation step of the prior art but to obtain a'very decided improvement in the yield of useful products.

Expressed in general terms therefore, the process of the present invention comprises condensing either the 3- or 4-nitrophthalic anhydride or a mixture of them with hydrazine sulfate in con- 'cen'trated sulfuric acid and then carrying out the molecular rearrangement in the solution. Reduction of the nitro to the amino compounds may be carried out by any suitable method, for example, by the aid of sodium hydrosulfide.

One of the principal advantages of not separating the 3- and 4-nitrophthalic acids in the process of the present invention lies in the fact that they can thereby be utilized directly in the sulfuric acid solution which results from the nitrating operation. This solution may be appropriately diluted with slightly weaker sulfuric acid and the subsequent steps carried out without any necessity for isolating the nitrated phthalic acids. If the sulfuric acid solution obtained in the nitrating operation is so used, it is of advantage to remove any nitrous or nitric acids remaining in the nitration mixture before carrying out the condensation with hydrazine sulfate. This may be readily carried out by bubbling a smal1 amount of sulfur dioxide therethrou-gh.

Condensation with hydrazine sulfate is carried out by adding the latter in solid form to the nitrophthalic anhydride in sulfuric acid solution. Heat is necessary to initiate the reaction but otherwise the latter proceeds smoothly and with noparticular technical difiiculty. Temperature ranges of from about 60 to 130 C. have been found to yield satisfactory results. Practically, however, it has been found best to limit the temperature range to about 85 to 100 C., at which temperatures the reaction proceeds at a suitable rate for industrial production. At the end of the heating period the products are found nitro-1,4-dioxo-tetrahydrophthalazines. Theoretically, they pass through the intermediate state of being nitroN-amino-phthalimides but as a practical consideration it cannot be stated whether or not this actually occurs.

The invention will be more fully illustrated in conjunction with the following example which is meant to be illustrative only and not by way of limitation. All parts are by weight unless otherwise noted.

Example 150 parts of sulfuric acid is heated to 95 C. and 143 parts of phthalic anhydride added thereto with stirring over a ten minute period. With thetemperature of the above slurry at 95 C., 238 parts of mixed acid (H2804 56.5%; HNOs 27%) isadded to the partially dissolved phthalic anhydride at such a rate that the temperature does not exceed 105 C. v The temperature of the reaction mixture is then maintained at 95-100 C. until the nitration is completed. Sulfur dioxide is-intro-duced into the hot reaction mixture until i a negative test for nitrate and nitrite is obtained.

The mixture is then diluted with 273 parts of sulfuric acid, and 130 parts of hydrazine sulfate is added. The mixture is then heated to 95 C.,

maintained at this temperature for several hours to insure completion of the rearrangement and on the chemiluminescence.

then poured into 1500 parts of ice. After stirring for 15 minutes, the cooled mixture is filtered and the residue washed with 500 parts of water. For

the reduction, the wet press cake of 5- and S-nitro- 1,4-dioxo-tetrahydrophthalazine is then slurried in 250 parts of Water and 5N sodium hydroxide is slowly added until the solution is alkaline tollitmus. The mixture is then heated to 60 C. and 96 parts of a 47.8% solution of sodium hydr-osulfide is added over a forty-five minute period. When the addition is complete, the temperature is raised to 95 C. and maintained at this point for several hours. After heating, the mixture is diluted with 1,000 parts of Water, filtered and the filtrate acidified with 5N sulfuric acid. The resulting precipitated mixture of 5- and 6-amino- 1,4-dioxo-tetrahydrophthalazine is filtered off and dried at C.

As produced by the process of the present invention, the amino-1,4-dioxo-tetrahydrophthalazines ordinarily contain sulfur which is precipitated when the reduction liquor is acidified with sulfuric acid. It has been found that the presence of the sulfur. has no detriment-aleffect If so desired, this sulfur may be readily eliminated, for example, the sulfur-containing material may be dissolved in alkali, filtered and reprecipi-tated by acidification. I l v As was pointed out-above, one of the advan tages of the present process lies in the utilization of the mixed anhydrides withoutisolating them. The vprocess however is not necessarily-solimited. Instead of starting with a mixture of 3-nitro and e-ni-trophthalic anhydrides as in the above example, either of the isomers, prepared by any suitable method may be employed. Either of the isomeric 3- or 4-nitr-ophthalic anhydrides maybe reacted with hydrazine sulfate'in sulfuric acid as described above, to produce the 5- or the 6-nitrolA-dioxo-tetrahydrophthalazines respectively.

Several important advantages areuobtained by the use of the persentproces-s, particularly when a mixture of the isomers is prepared. In that case, all the stepwise reactions, starting from the phthalic anhydride and ending up With the nitro-dioxo-tetrahydrophthalazines may be performed in the same medium, in the same vessel, without isolation of any intermediate product. Even when the isom'ersare separated, the process still has the important advantage that the conversion of the particular nitrophthalic anhydr-ide to the corresponding nitro-dioxo-tetrahydrophthalazine can be carried out insolution in a technically feasible manner.

As was also pointed out above, in the preparation of a chemiluminescent composition of matter, to be used e. g. as sea marker, it is not necessary to separate the two isomers. The mixture of the ,5- land G-amino-lA-dioxo-tetrahydrophthalazines is for all practical purposes equiva lent in efficiency to the pure 5- amino isomer. Since such a luminescent mixture can be prepared in a considerably higher yield than the pure isomer and at a considerably lower cost, not only as to the materials used, but also as far as the conversion cost is concerned, the advantage in so doing is quite apparent.

We claim: 7

1. A process of preparing a mixture of 5- and G-nitro-1,4-dioxotetrahydr-oph-thalazines which comprises reacting a mixture, obtained by nitrating phthalic anhydride with a mixture of concentrated sulfuric and nitric acids and then bub- 5 6 bling sulfur dioxide therethrough for a sufficient time to destroy any residual nitric acid, with REFERENCES CITED hydrazine sulfate in concentrated sulfuric acid. The following references are of record in the 2. A mixture of 5- and G-nitro-lA-dioxotetrafile of this patent:

hydrophthalazines obtained by reacting a mixture, obtain-ed by nitrating phthalic 'anhydride 5 :5 g i gg; with a mixture of concentrated sulfuric and Chem Abstracts Vo1'31pageS2188 8 nitric acids and then bubbling sulfur dioxide Chem? Abstracts Vol 2 page 1684 therethrough for a suflicient time to destroy any 1 Grogg'ms b in Orga'nic Chem residual nitric acid, with hydrazine sulfate in 10 istryn pages 83 84 (1938) f concentrated sulfuric acid.

HAROLD T. LACEY. ROBERT E. BROUILLARD. 

